Iphone 4s suddenly not taking/sending iMessages

I have had my 4s since october with little issue. Starting yesterday my imessages stopped working between me and other iphone users. I checked my settings and it now says "waiting on activation". I tried several of the tips in the discussion forum, when this problem seemed widespread last november. I haven't seen anything recent.

I've logged in and out of Apple ID, rebooted, reset, everything and my imessages will not come back!!! Help. I just did the latest iphone update thinking that might fix it but it didnt.